1. How Big Is a Typical Japanese Horse Mackerel?
When people go fishing, the horse mackerel they commonly catch is usually between 20 cm and 30 cm in body length [1]. In very rare cases, there are reports of individuals growing to about 50 cm [1]. It is said that horse mackerel that live a long time can survive for about 6 to 7 years [1].
2. How Anglers Name Horse Mackerel by Their Size
Among fishing enthusiasts, the name used for a horse mackerel changes depending on its size [2]. If the fish exceeds 30 cm, it is called a "shaku-aji," a term derived from the old Japanese unit of length called the "shaku" [2]. If the fish grows even larger, anglers sometimes jokingly call it a "mega-aji," "giga-aji," or "tera-aji," mimicking computer storage terms [2]. However, these names are not strict rules; the way people refer to these sizes varies depending on the person and the region [2].
3. Why Are the Horse Mackerel in Hayamizu So Large?
Hayamizu is located in the middle of the Uraga Channel, which is the entrance to Tokyo Bay [3]. The tidal currents in this area are very fast [3]. To avoid being swept away, the horse mackerel must constantly move their bodies to stay in place. As a result, they grow into fish with well-developed muscles [3]. Because their bodies are thick and bulging around the belly, anglers also call these fish "buta-aji" [6].
4. Fishing Methods Used to Catch Large Horse Mackerel
There are several methods used to target large horse mackerel. One method is called "bishi-aji." This involves scattering crushed sardine bait little by little to lure the fish [4][7]. Another method is "bachikon." This combines a heavy sinker with a light rig (a jig head with a worm) to target deep waters from a boat [4][8]. A third method is "ajing," which uses lures, or artificial bait, and can be done from the shore or from a boat [4]. The specific spots where these large fish are found are often kept secret by the boat captains who take anglers out.
5. Why Some Horse Mackerel Look Yellowish
Horse mackerel are divided into two groups: those that travel through the wide ocean and those that settle in narrow bays and do not move much [5]. The settled horse mackerel sometimes have bodies that turn yellowish and are called "kin-aji," or "gold mackerel" [5]. Because they grow in places where food is abundant, it is said that their meat is rich in fat [5].
6. How to Compare Horse Mackerel Sizes at the Supermarket
If you see horse mackerel lined up at the fish counter in a supermarket, look at their size. If there are several, it is interesting to compare their sizes and check if their body color looks golden.